Please include the day of the week along with the dateGreat - free pastry! When? The 23rd? What day is that?
I had to look it up. But, there was no need for me to have to do that. I tweaked the above announcement on the right to show the day. The day and the date are also grouped together as a unit on one line.

Designers, writers, and editors should always include the day of the week with the date.
Even if the copy given to you does not have the day, please add it. If there is not enough room in the given space, explore options - abbreviate the day or the month (we are so familiar with day and month abbreviations that comprehension should not be affected).
Instead of:January 29, 7:30pm, Music Hall
Include the day:Thursday, January 29, 7:30pm, Music Hall
Or if space is a problem:Thurs, Jan 29, 7:30p, Music Hall

Here's whyWe often plan our schedules based on the day. Bridge on Tuesday nights, classes on MWF or TT, weekly meetings on Monday mornings, etc. When planning upcoming events and activities, we all think most often in days, not dates. Using just the date requires the reader to figure out what day that is so they can schedule it. Be more considerate and more clear - save the reader some trouble and just give them the day.
It is more familiar - it's how we speak with our friends:"Lets go to the concert on Thursday."
"Okay."
That is easier to comprehend than:"Lets go to the concert on the 29th."
"What day is that?"
"Thursday."
"Okay."

• There is no advantage to omitting the day of the week.
• There are advantages to including the day of the week: more respect for the reader and clearer communication.

More examples
This Visitor Pass denotes the date and time I could visit the new 9/11 Memorial at the World Trade Center. It should also have included the day so people could more easily plan their trips. I looked at a calendar, checked what day November 10th was, and wrote that day on my ticket.

I got this letter from Mercy Clinic about some info sessions for Medicare. But, only the date was given, not the day of the week. Stating only a date is inconsiderate to the reader - especially in this case, many recipients are retired and not on a routine schedule. In any case, the reader must then question, "What day is that?"
Great designers respect the reader enough to not make them work - just give them the day. Improvements to the info in the Mercy letter (shown below):
• Can see at a glance that there are 6 sessions, not 3.
• Can see easily that sessions are on Monday and Thursday.
• Aligned the times for easier scanning down the column.
• Don't need all those pesky periods after a, p, and m.
• Separated the days and dates from the location.
• Provided a better description of the location.

I got this invitation in the mail - what fun - 50s music at the Art Museum, with cocktails. It sounds like a great time. I want to go. When is it? August 15? When is that - a Thursday, a Saturday? Why didn't they tell me so I could mentally plan my schedule? I plan my schedule in days of the week rather than dates.

Above: The Oklahoman mobile newspaper: existing and proposed. I wrote them about adding the day of the week to the listings on their iPad version (a daily paper ought to include the day) I included the two images above as an example of the improvement. No response. I wrote again. Nothing. Many weeks later, a former student saw this essay and wrote his boss, the Creative Director. That finally nudged them to act:

This mailer tells us there's a big event on the 25th. Its so easy for designers to respect their readers by giving us the day - in this case, it is a Sunday.

I donate blood regularly (its just the right thing to do). I went online to make an appointment and nowhere in the process did the blood center tell me on what day the blood drive would be held. I had to perform a separate function of opening and checking a calendar to determine what day the 23rd would be. There is no reason I or any user of their website should have to do that - just include the day with the date.
Reminder: we schedule our lives in days, not dates.

The OSU Museum of Art opened an exhibit of a Frank Lloyd Wright house and sponsored four programs:
The text of the program details were in prose form - one paragraph per, and it wasn't easy to find the important info.
Improvements:
• Add the day of the week.
• Add a line break after the title and after the time & place.
• Bold the important info.

Below: I not only added the day of the week, but also changed the text to read in a more logical, clearer order. 'Leaving for OKC' is redundant since the headline says 'to OKC'. Changed that to read 'Leaving OSU', which is more appropriate for the student to understand.

This place got it right
The flier on the right is the actual one - I deleted the day for the example on the left. See how much clearer it is when the day is included. They also set the time well - 5pm - with no spaces, rather than 5 P. M.

Another correct example. This was from Target, 2011:

In the example below, the two columns on the left include both the day and the date, the columns on the right have just the date. Again, see how much clearer it is. It respects the reader and his/her time.
The two ads on the left include the day, the two on the right do not. Notice that there is plenty of room to include the day of the week.Please include the day of the week whenever you print a date of upcoming events.Thank you. And please spread the word. www.jamesrobertwatson.com/daywithdate.html